Implanted subcutaneous access ports can be difficult to locate, isolate, grasp and target with needles during access, especially given the wide variety of port geometries in the market place. Problems that may occur during access include accidental needle sticks of the clinician's fingers, poor targeting resulting in a missed septum and/or punctured catheter. Additionally, the sealing quality of a port septum may be compromised by repeated access punctures in the same location, which can occur with current access methods given the difficulty of visualizing and recording the repeated port needle access locations.
U.S. Pat. No. 5,620,419 to Lui et al. discloses a noninvasive, perforate, self-centering locator which facilitates engagement of a needle or cannula with a subcutaneously implanted access port. The locator is exemplified by a port stabilizer ring having a central opening. During use, the stabilizer ring is pressed on the skin over the site of the port, and simultaneously visually locates the septum of the port for the user while stabilizing the port with respect to the skin and underlying tissues, permitting ready penetration of the skin and septum by the needle or cannula.
However, Lui does not provide for protection of the user of the locator against inadvertent sticks from the needle or cannula. Furthermore, the wide configuration of the ring of Lui makes it difficult to apply suitable pressure to the skin by the user to locate a port which may be deeply implanted in subcutaneous tissue. Moreover, Lui does not provide any means for determining and/or avoiding prior penetration locations of the port septum with the needle or cannula, which could expedite septum failure if the same penetration locations are used repeatedly.